The invention relates to the field of blood sampling devices, and particularly those adapted for multiple sample collection.
Various valve assemblies have been designed for controlling the direction of flow of fluids. These include, for example, ball and seat valves, duckbill valves, and cup-shaped or conical valves. The latter two valves operate by compressing or folding their elastomeric skirts under sufficient pressure, thereby permitting fluid to pass by in the forward direction. Pressure in the opposite direction tends to expand the flexible portion into sealing contact with the conduit walls. U.S. Pat. No. 2,913,000 discloses a cup-shaped flow control valve which operates in this manner.
Previous valve assemblies have not been applied to blood sampling devices in providing a simple structure for preventing backflow and allowing multiple sampling.
Prior multiple sampling assemblies also fail to disclose means to prevent cocking and malfunction of the valve.
Other blood sampling devices known to the art have features which enable their use as both check valves (preventing backflow) and multiple sampling device (preventing forward flow under tourniquet pressure). The latter feature enables the user to exchange evacuated blood collection tubes without leakage occuring due to venous or tourniquet pressure. The use of a simple, inexpensive cup valve in conjunction with an assembly specifically adapted to utilize its advantageous features has not previously been disclosed.